Comtech EF Data CDM-700 - Manual (Page 251)

Appendix F. E
b
/N
0
MEASUREMENT
Although the CDM-700 calculates and displays the value of receive E
b
/N
0
on the front panel of
the unit, it is sometimes useful to measure the value using a spectrum analyzer, if one is available.
The idea is to accurately measure the value of (Co+No)/No, (Carrier density + Noise
density/Noise density). This is accomplished by tuning the center frequency of the Spectrum
analyzer to the signal of interest, and measuring the difference between the peak spectral density
of the signal (the flat part of the spectrum shown) and the noise density.
To make this measurement:
• Use a vertical scale of 1 or 2 dB/division.
• Set the Resolution Bandwidth of the Spectrum Analyzer to < 20 % of the symbol rate.
F–1